Methods for combining light emitting devices in a package and packages including combined light emitting devices

ABSTRACT

Methods of forming a light emitting device package assembly include defining a chromaticity region in a two dimensional chromaticity space within a 10-step MacAdam ellipse of a target chromaticity point, and subdividing the defined chromaticity region into at least three chromaticity subregions, providing a plurality of light emitting devices that emit light having a chromaticity that falls within the defined chromaticity region, selecting at least three of the plurality of light emitting devices, wherein each of the three light emitting devices emits light from a different one of the chromaticity subregions. The at least three light emitting devices are selected from chromaticity subregions that are complementary relative to the target chromaticity point to at least one other chromaticity subregion from which a light emitting device is selected.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 12/425,855, filed Apr. 17, 2009, now U.S. Pat. No.7,967,652 entitled “METHODS FOR COMBINING LIGHT EMITTING DEVICES IN APACKAGE AND PACKAGES INCLUDING COMBINED LIGHT EMITTING DEVICES,” whichapplication claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/153,889, filed Feb. 19, 2009, entitled“METHODS FOR COMBINING LIGHT EMITTING DEVICES IN A PACKAGE AND PACKAGESINCLUDING COMBINED LIGHT EMITTING DEVICES,” the disclosures of which arehereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to lighting, and more particularly toselecting lighting components used in lighting assemblies and lightemitting packages including selected lighting components.

BACKGROUND

Solid state lighting devices are used for a number of lightingapplications. A lighting panel including solid state lighting sourcesmay be used, for example, for general illumination in a lightingfixture, or as a backlighting unit for an LCD display. Lighting panelscommonly employ an arrangement of multiple light emitters such asfluorescent tubes and/or light emitting diodes (LED). An importantattribute of the multiple light emitters may include uniformity of colorand/or luminance in displayed output. In some cases, the light emittersmay include multiple LED chips.

Presently, LED chips may be tested and grouped and/or binned accordingto their respective output and/or performance characteristics prior tobeing mounted in an LED package. The grouping may be performed using,for example, chromaticity values, such as the x, y values used in theCIE 1931 chromaticity diagram that was created by the InternationalCommission on Illumination in 1931. In this manner, each light emittingdevice may be characterized by x, y coordinates. Emitters having similarx, y values may be grouped or binned to be used together, i.e., to bemounted together in a single LED package.

SUMMARY

A method of forming a light emitting device assembly according to someembodiments includes providing a light emitting device assembly body,defining a chromaticity region in a two dimensional chromaticity spacethe chromaticity region may be defined within a 10-step MacAdam ellipseof a target chromaticity point, and subdividing the defined chromaticityregion into at least three chromaticity subregions. A plurality of lightemitting devices that emit light having a chromaticity that falls withinthe defined chromaticity region may be provided, and at least three ofthe plurality of light emitting devices may be selected. Each of thethree light emitting devices may have a chromaticity point in adifferent one of the chromaticity subregions and the at least threelight emitting devices may be selected from chromaticity subregions thatmay be complementary relative to the target chromaticity point to atleast one other chromaticity subregion from which a light emittingdevice may be selected The selected light emitting devices may bemounted on the light emitting device assembly body.

The target chromaticity point may be on the black body locus and mayhave a correlated color temperature between 2600K and 6600K.

Selecting the at least three light emitting devices may includeselecting at least two sets of light emitting devices. Each set of lightemitting devices may include at least two light emitting devicesselected from chromaticity subregions that may be complementary relativeto the target chromaticity point.

The chromaticity region may encompass a defined bin in the twodimensional chromaticity space, and the defined bin may include aquadrangle on a two dimensional chromaticity space that may have a widthequal to a major axis of a 7-step MacAdam ellipse in the two dimensionalchromaticity space.

Each of the at least three chromaticity subregions may at leastpartially overlap the defined bin.

A combined light from the at least three light emitting devices may fallwithin a target chromaticity region that may be a subset of the definedbin.

The defined chromaticity region may be larger than and encompasses thedefined bin, and the target chromaticity region touches an edge of thedefined bin.

The target chromaticity region may have an area on a two dimensionalchromaticity space that may be about the size of a 2-step MacAdamellipse in the two dimensional chromaticity space.

The target chromaticity region may have an area on a two dimensionalchromaticity space that may be smaller than a 2-step MacAdam ellipse inthe two dimensional chromaticity space.

The light emitting devices may include phosphor-coated blue lightemitting device chips.

The methods may further include defining a second chromaticity region ina two dimensional chromaticity space the second chromaticity region maybe defined within a 10-step MacAdam ellipse of a second targetchromaticity point and the second chromaticity region does not overlapwith the first chromaticity region, and subdividing the secondchromaticity region into at least three second chromaticity subregions,providing a second plurality of light emitting devices that emit lighthaving a chromaticity that falls within at least one of the secondchromaticity subregions, and selecting at least three of the secondplurality of light emitting devices. Each of the three light emittingdevices of the second plurality of light emitting devices emits lightfrom a different one of the second chromaticity subregions. The selectedlight emitting devices of the second plurality of light emitting devicesmay be on the light emitting device package body.

The second chromaticity region may include light having a dominantwavelength greater than about 600 nm.

The methods may further include defining a third chromaticity region ina two dimensional chromaticity space, and subdividing the thirdchromaticity region into at least three third chromaticity subregionsthe third chromaticity region does not overlap with the first and/orsecond chromaticity regions, providing a third plurality of lightemitting devices that emit light having a chromaticity that falls withinat least one of the third chromaticity subregions, and selecting atleast three of the third plurality of light emitting devices. Each ofthe three light emitting devices of the third plurality of lightemitting devices emits light from a different one of the thirdchromaticity subregions. The selected light emitting devices of thethird plurality of light emitting devices may be mounted on the lightemitting device package body.

The first chromaticity region may include light having a chromaticitypoint that may be within a 10-step MacAdam ellipse of a point on theblack body locus having a correlated color temperature between 2600K and6600K, the second chromaticity region may include light having adominant wavelength greater than about 600 nm, and the thirdchromaticity region may include light having x, y color coordinateswithin an area on a 1931 CIE Chromaticity Diagram defined by pointshaving coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42,0.42), (0.36, 0.38).

The defined subregions include a plurality of pairs of complementarysubregions, respective subregions in a pair of complementary subregionsmay be arranged opposite a center point of the chromaticity region fromone another, selecting the at least three of the plurality of lightemitting devices may include selecting at least four of the plurality oflight emitting devices from at least four chromaticity subregions inpairs from respective pairs of complementary subregions.

Selecting a pair of light emitting device from one pair of complementarysubregions may include selecting a first light emitting device having afirst luminous flux from a first subregion that may have a center pointthat may be located a first distance from a center point of thechromaticity region, and selecting a second light emitting device havinga second luminous flux from a second subregion that may be complementaryto the first subregion and that may have a center point that may belocated a second distance from a center point of the chromaticityregion, the first distance may be smaller than the second distance andthe first luminous flux may be larger than the second luminous flux.

The at least three light emitting devices may be selected from at leastthree chromaticity subregions that may be complementary relative to thetarget chromaticity point.

A light emitting device assembly according to some embodiments includesa light emitting device assembly body, and at least three light emittingdevices on the assembly body. Each of the at least three light emittingdevices emits light having a chromaticity that falls within a definedchromaticity region in a two dimensional chromaticity space. Thechromaticity region may be defined within a 10-step MacAdam ellipse of atarget chromaticity point that may be on the black body locus and thatmay have a correlated color temperature between 2600K and 6600K. Thedefined chromaticity region may be subdivided into at least threechromaticity subregions. The at least three light emitting devices emitlight when energized that falls within chromaticity subregions that maybe complementary relative to the target chromaticity point to at leastone other chromaticity subregion in which a light emitting device in thelight emitting device assembly emits light.

A lighting fixture according to some embodiments includes a lightemitting device package assembly as described above.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate certain embodiment(s) of theinvention. In the drawings:

FIG. 1A is a plan view of a packaged light emitting diode according tosome embodiments.

FIG. 1B is a perspective view of a packaged light emitting diodeaccording to some embodiments.

FIG. 1C illustrates an LED die that can be used in a packaged lightemitting diode according to some embodiments.

FIG. 2 is a chromaticity diagram illustrating a chromaticity regioncorresponding to light emitters having similar chromaticity coordinatesaccording to some embodiments.

FIG. 3A is a plan view of a packaged light emitting diode according tofurther embodiments.

FIG. 3B is a chromaticity diagram illustrating a plurality ofchromaticity regions corresponding to different groups of light emittershaving similar chromaticity coordinates according to some embodiments.

FIG. 4A is a plan view of a packaged light emitting diode according tofurther embodiments.

FIG. 4B is a chromaticity diagram illustrating a plurality ofchromaticity regions corresponding to different groups of light emittershaving similar chromaticity coordinates according to some embodiments.

FIG. 5 is a chromaticity diagram including a chromaticity region that issubdivided into chromaticity subregions according to some embodiments.

FIG. 6A illustrates standard chromaticity regions, or bins, on achromaticity diagram.

FIG. 6B illustrates standard chromaticity bins on a chromaticity diagramthat have been further subdivided into smaller bins.

FIG. 7 illustrates a chromaticity region that is subdivided intosubregions according to some embodiments.

FIGS. 8A, 8B and 8C illustrate selection of light emitters fromchromaticity regions that are subdivided into subregions according tosome embodiments.

FIG. 9 schematically illustrates a system for assembling light emittingdiode packages according to some embodiments.

FIG. 10 illustrates luminous flux bins that can be used in accordancewith some embodiments.

FIG. 11 illustrates a portion of a chromaticity space including aplurality of chromaticity regions including a target chromaticity regionaccording to some embodiments.

FIG. 12 illustrates a lighting panel for general illumination includinga plurality of light emitting device packages according to someembodiments.

FIG. 13 is a flowchart illustrating operations of systems and/or methodsaccording to some embodiments.

FIGS. 14A, 14B, 14C, 14D, 14E and 14F are simulation results thatillustrate various combinations of sets of complementary light emittersaccording to some embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention now will be described more fullyhereinafter with reference to the accompanying drawings, in whichembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer or region to another element, layer or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”“comprising,” “includes” and/or “including” when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

Reference is now made to FIGS. 1A, 1B and 1C. FIG. 1A is a schematicplan view. FIG. 1B is a perspective view illustrating a light emittingdevice (LED) package 100 including multiple light emitting devices (orlight emitters) 120A-120D that are selected and grouped according tosome embodiments of the present invention. FIG. 1C illustrates anexample of a light emitter 120 including an LED chip 122 that includestop and bottom anode/cathode contacts 126A, 126B and that is coated witha wavelength conversion phosphor 124 according to some embodiments. Insome embodiments, the light emitter 120 may itself include a packagedsingle or multi-chip LED device, and the LED package 100 may include afixture, panel or luminaire in which a plurality of packaged lightemitters 120 are mounted.

The LED package 100 may include a multi-chip module as described, forexample, in U.S. patent application Ser. No. 12/154,691 filed May 23,2008, the disclosure of which is incorporated herein by reference as iffully set forth herein in its entirety. In some embodiments, the lightemitters 120A-120D may have both anode and cathode contacts on the sameside of the device. Accordingly, the present invention is not limited todevices including light emitters having a vertical device structure withanode and cathode contacts on opposite sides of the device.

In particular embodiments, the LED package 100 includes multiple lightemitters 120A-120D mounted within a package body 110. Although fourlight emitters 120A-120D are illustrated, the package 100 could includemore or fewer light emitters therein. A lens 130 may be affixed over thelight emitters 120A-120D to provide a desired angular emission patternof light from the light emitters 120A-120D, and/or to increase lightextraction from the LED package 100. In some embodiments, the lightemitters 120A-120D may be covered or coated with a wavelength conversionmaterial, such as a phosphor, that converts at least a portion of lightemitted by the light emitters 120A-120D to a different wavelength orcolor. A plurality of electrical leads 135 provide electrical connectionto the light emitters 120A-120D in the package 100. Each of the lightemitters 120A-120D in the package 100 may be individually addressable.That is, the package may include separate anode/cathode leads from amongthe electrical leads 135 for each of the light emitters 120A-120D.Having individually addressable light emitters may permit the lightemitters to be individually controlled, for example driven at differentcurrent levels, which may enable a lighting system to compensate forbrightness variations among the light emitters in a given package 100 toachieve a desired color point.

In particular embodiments, the LED package 100 may include a multi-chipLED package, such as an MC-E LED available from Cree, Inc., the assigneeof the present invention.

In particular embodiments, the LED package 100 may include four phosphorcoated power LED chips having dimensions of about 1000 μm×1000 μm ormore. Some embodiments provide a 7 mm×9 mm LED package including four1.4 mm×1.4 mm phosphor coated power LED chips. Such a package may becapable of generating more than 1,000 lumens of light output at 700 mAusing approximately 9.8 W of power. One thousand lumens is approximatelyequivalent to the light produced by a standard 75 watt incandescentlight bulb.

Some embodiments may provide binning and chip selection techniques foruse in LED package manufacturing that may provide extremely tightlycolor-matched LEDs in an LED package. In particular, binning and chipselection techniques according to some embodiments may provide a tighter(i.e. narrower or smaller) color distribution than previously available,allowing users to address applications with very tight colorrequirements and/or reducing waste of LED chips that previously couldnot be used in a particular packaging application. In particularembodiments, a color distribution can be achieved that is about 79%tighter than can be achieved with standard binning techniques.

In some embodiments, the light emitters 120A-120D may be grouped and/orselected for inclusion in a particular LED package 100 responsive to thecombined chromaticity and/or luminous flux values of the light emitters120A-120D. Chromaticities of the light emitters 120A-120D may beselected so that the combined light, that is a mixture of light from thelight emitters 120A-120D, may have a desired chromaticity. In thismanner, the perceived color of light generated by the LED package 100may appear to have a desired chromaticity, e.g. white, based on theapparent chromaticity of the combination, even if none (or fewer thanall) of the light emitters 120A-120D individually emits light having thedesired chromaticity. Furthermore, in some embodiments, the luminousflux of the light emitters 120A-120D may be selected so that thecombined mixture of light has a desired luminous flux level.

For example, reference is made to FIG. 2, which is a two-dimensionalchromaticity diagram illustrating a chromaticity region 146 within achromaticity space 140. It will be appreciated that a chromaticitydiagram is a two-dimensional representation of all visible colors. Eachvisible color, which has a distinct hue and saturation, can berepresented by a point in the diagram. Various chromaticity spaces havebeen defined, including the 1931 CIE chromaticity space and the 1976 CIEchromaticity space created by the International Commission onIllumination (CIE).

The light emitted by a light emitter 120A-120D may be represented by apoint on a chromaticity diagram. Consequently, a region on achromaticity diagram may represent light emitters having similarchromaticity coordinates.

The chromaticity region 146 is subdivided into multiple chromaticitysubregions (or simply subregions) 146A-146D. The subregions 146A-146Dmay correspond to multiple groups of light emitters having similarchromaticity coordinates. As illustrated in FIG. 2, the chromaticityspace 140 may be defined in terms of u′ and v′ axes 144, 142 such thatany point in the color space may be expressed as a coordinate pair (u′,v′). It will be appreciated that the chromaticity region 146 shown inFIG. 2 may be in any desired location within the chromaticity space 140and may have any desired size or shape. The size, shape and location ofthe chromaticity region 146 in FIG. 2 are arbitrary and are shown forillustrative purposes only.

According to some embodiments, an LED package 100 includes a pluralityof N light emitters 120A-120D. Although the LED package 100 of FIG. 1 isillustrated as including four (4) light emitters, it will be appreciatedthat N could be any number greater than two (2). Each of the N lightemitters 120A-120D has a chromaticity that falls within one of Nsubregions 146A-146D defined within a chromaticity region 146. Thecombined light from the N light emitters 120A-120D may fall within atarget chromaticity region 148 that is defined within and is smallerthan the chromaticity region 146 within which the N subregions 146A-146Dare defined.

For example, an LED package 100 according to some embodiments mayinclude first to fourth light emitters 120A to 120D that are selectedbased on their chromaticity points falling within one of first to fourthemitter group subregions 146A-146D. For example, one of the lightemitters 120A may have a chromaticity that falls within a firstsubregion 146A, one of the light emitters 120B may have a chromaticitythat falls within a second subregion 146B, one of the light emitters120C may have a chromaticity that falls within a third subregion 146C,and one of the light emitters 120D may have a chromaticity that fallswithin a fourth subregion 146D.

It will be appreciated, however, that it may not be necessary for an LEDpackage 100 to include a light emitter 120A-120D from each of thedefined subregions 146A-146D, depending on the chromaticities of theselected light emitters 120A-120D. Furthermore, each of the lightemitters 120A-120D does not have to be in a unique subregion 146A-146D.For example, more than one of the light emitters 120A-120D may fallwithin a single subregion 146A-146D.

In some embodiments, the subregions may be defined such that eachsubregion in the plurality of subregions shares a boundary line with atleast two other subregions. Also, each subregion may at least partiallyoverlap the target chromaticity region 148. In some embodiments, thesubregions 146A-146D may completely fill the chromaticity region 146, sothat a chromaticity point in the chromaticity region 146 falls within atleast one defined subregion.

Accordingly, some embodiments define a chromaticity region 146 that islarger than and encompasses a target chromaticity region 148. Thechromaticity region 146 is further divided into a plurality of Nsubregions 146A to 146D that are arranged in a two-dimensional matrix ofsubregions. An LED package 100 includes a plurality of N light emitters120A to 120D, each of which has a chromaticity that falls within one ofthe N subregions 146A to 146D.

In some embodiments, the chromaticity of an individual light emitter120A-120D may be determined based on the color of light emission fromthe light emitter 120A-120D without any color conversion or shiftingusing phosphors or other luminophoric material. Alternatively, in someembodiments, the chromaticity of an individual light emitter 120A-120Dmay be determined based on the combined color of light emission from thelight emitter 120A-120D and of light emission from a phosphor that isstimulated by the emission from the light emitter 120A-120D. Forexample, in some embodiments, the light emitters 120A-120D may compriseblue and/or ultraviolet LEDs that are coated with a phosphor orphosphor-bearing material that is arranged to receive at least somelight emitted by the light emitters 120A-120D and to responsively emitlight having a different wavelength. The combined light emitted by thelight emitter and the phosphor may appear white. Such color conversionis well known in the art.

Phosphor coating of LED chips is described, for example, in U.S. Pat.Nos. 6,853,010 and 7,217,583, the disclosures of which are incorporatedherein by reference as if fully set forth herein.

In some embodiments, one or more of the light emitters 120A-120D may becoated with phosphor, while one or more of the light emitters 120A-120Dmay not be coated with phosphor. In some embodiments, none of the lightemitters 120A-120D may be coated with phosphor.

In some embodiments, light emitters 120A-120D may be selected forinclusion in an LED package 100 based on their chromaticity points beingabout equidistant from the target chromaticity region 148, or a desiredchromaticity point within the target chromaticity region 148, or beingin subregions 146A-146D that are about equidistant from the desiredchromaticity point or region. However, it will be appreciated that thechromaticity points of the light emitters 120A-120D need not beequidistant from the desired chromaticity point or region.

In some embodiments, the desired chromaticity point or region 148 may bedifferent from the chromaticity of light emitted by some or all of thelight emitters 120A-120D in the package 100. For example, in someembodiments, an LED package 100 includes four light emitters 120A-120D.Some, e.g., three, of the light emitters 120A-120C may include bluelight emitting diodes coated with a yellow phosphor and having acombined light emission (chip plus phosphor) that appears yellow-greento an observer. As used herein, “white light” generally refers to lighthaving a chromaticity point that is within a 10-step MacAdam ellipse ofa point on the black body locus (BBL) having a correlated colortemperature (CCT) between 2600K and 6600K, while “yellow-green light”generally refers to light having x, y color coordinates within an areaon a 1931 CIE Chromaticity Diagram defined by points having coordinates(0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38), asdescribed in detail in U.S. Pat. No. 7,213,940, the disclosure of whichis incorporated herein by reference. Thus, the target chromaticityregion 148 for combined light from the three light emitters 120A-120Cmay not be in a region of a chromaticity space that is conventionallydesignated as “white.” The fourth light emitter may comprise a red LEDthat emits light at a wavelength selected such that combined light fromall four light emitters 120A-120D appears white to an observer, and insome embodiments falls along the black body locus.

Referring to FIG. 3A, an LED package 200 that includes multiple groupsof multiple light emitters is illustrated. For example, the LED package211 includes a first group of 24 white or near-white light emitters 220and a second group of eight red light emitters 230 for a total of 32light emitters. Light emitters in each group of light emitters may beselected in accordance with embodiments of the invention. For example,an LED package 200 may include a plurality of “white” LED chips 220comprising phosphor-coated blue emitting LED chips and a plurality ofred light emitting LED chips 230. As used herein, “red light” refers tovisible light having a dominant wavelength of about 600 nm or more.Referring to FIG. 3B, the white LED chips 220 may be selected from aplurality of subregions 246A-246D that are defined in a chromaticityregion 246 within a chromaticity space 240 that includes a first targetchromaticity region 248 for combined light emitted by the white lightemitters. Furthermore, the red light emitters 230 may be selected from aplurality of subregions 256A-256D that are defined in a chromaticityregion 256 that includes a second target chromaticity region 258 ofcombined light emitted by the red light emitters 230. As the combinedlight emitted by the white light emitters falls within the first targetchromaticity region 248 and the combined light emitted by the red lightemitters 230 falls within the second target chromaticity region 258, thecolor of the total combined light emitted by the LED package 200 may bemore consistent overall.

It will be appreciated that the chromaticity regions 246, 256 shown inFIG. 3B may be in any desired location within the chromaticity space 240and may have any desired size or shape. The size, shape and location ofthe chromaticity regions 246, 256 in FIG. 3B are arbitrary and are shownfor illustrative purposes only.

As a further example, referring to FIGS. 4A and 4B, an LED package 300may include a plurality of “white” LED chips 310 comprisingphosphor-coated blue emitting LED chips, a plurality of yellow-green LEDchips 320 comprising phosphor-coated blue emitting LED chips and aplurality of red emitting LED chips 330. The white LED chips 310 may beselected from a plurality of subregions 346A-346D that are defined in achromaticity region 346 within a chromaticity space 340 that includes atarget chromaticity region 348 of combined light emitted by the whitelight emitters 310. The yellow-green LED chips 320 may be selected froma plurality of subregions 356A-356D that are defined in a chromaticityregion 356 of the chromaticity space 340 that includes a targetchromaticity region 358 of combined light emitted by the yellow-greenlight emitters. The red LED chips 330 may be selected from a pluralityof subregions 366A-366D that are defined in a chromaticity region 366 ofthe chromaticity space 340 that includes a target chromaticity region368 of combined light emitted by the red light emitters 330. Therespective combined colors of the white, yellow-green and red lightemitters may fall within the target chromaticity regions 348, 358. 368.Accordingly, the color of combined light emitted by the LED package 300may be more consistent.

It will be appreciated that the chromaticity regions 346, 356 and 366shown in FIG. 4B may be in any desired location within the chromaticityspace 340 and may have any desired size or shape. The size, shape andlocation of the chromaticity regions 346, 356, 366 in FIG. 4B arearbitrary and are shown for illustrative purposes only.

Referring to FIG. 5, a target chromaticity region 148 can be defined asa region that is within and encompassed by a chromaticity region 146that is defined in the proposed ANSI standard C78.377A for chromaticityof solid state light emitting devices. For example, in some embodiments,the chromaticity region 146 may encompass a point on the black bodylocus (BBL) having a color temperature of about 3050K. While FIG. 5illustrates a chromaticity region 146 as represented on a 1976 CIE u′v′chromaticity diagram, the chromaticity region 146 may correspond to aregion encompassing a point on the BBL of a 1931 CIE x,y chromaticitydiagram. In some embodiments, the chromaticity region 146 may be boundedby a quadrilateral defined by points having the following (x,y)coordinates on a 1931 CIE chromaticity x,y diagram: A (0.4147,0.3814); B(0.4299,0.4165); C (0.4562,0.4260); D (0.4373,0.3893).

A plurality of possible chromaticity regions, as represented on 1931 CIEchromaticity diagrams, are illustrated in FIG. 6A, on which emittergroup regions 3A-3D, 4A-4D, 5A-5D, 6A-6D and 7A-7D are shown. Numericdefinitions of the (x,y) coordinates of these emitter group regions areshown in the following Table:

TABLE 1 Emitter Group Regions 3A-3D to 8A-8D Region x y Region x yRegion x y Region x y 3A 0.3371 0.3490 3B 0.3376 0.3616 3C 0.3463 0.36873D 0.3451 0.3554 0.3451 0.3554 0.3463 0.3687 0.3551 0.3760 0.3533 0.36200.3440 0.3428 0.3451 0.3554 0.3533 0.3620 0.3515 0.3487 0.3366 0.33690.3371 0.3490 0.3451 0.3554 0.3440 0.3428 4A 0.3512 0.3465 4B 0.35290.3597 4C 0.3615 0.3659 4D 0.3590 0.3521 0.3529 0.3597 0.3548 0.37360.3641 0.3804 0.3615 0.3659 0.3615 0.3659 0.3641 0.3804 0.3736 0.38740.3702 0.3722 0.3590 0.3521 0.3615 0.3659 0.3702 0.3722 0.3670 0.3578 5A0.3670 0.3578 5B 0.3702 0.3722 5C 0.3825 0.3798 5D 0.3783 0.3646 0.37020.3722 0.3736 0.3874 0.3869 0.3958 0.3825 0.3798 0.3825 0.3798 0.38690.3958 0.4006 0.4044 0.3950 0.3875 0.3783 0.3646 0.3825 0.3798 0.39500.3875 0.3898 0.3716 6A 0.3889 0.3690 6B 0.3941 0.3848 6C 0.4080 0.39166D 0.4017 0.3751 0.3941 0.3848 0.3996 0.4015 0.4146 0.4089 0.4080 0.39160.4080 0.3916 0.4146 0.4089 0.4299 0.4165 0.4221 0.3984 0.4017 0.37510.4080 0.3916 0.4221 0.3984 0.4147 0.3814 7A 0.4147 0.3814 7B 0.42210.3984 7C 0.4342 0.4028 7D 0.4259 0.3853 0.4221 0.3984 0.4299 0.41650.4430 0.4212 0.4342 0.4028 0.4342 0.4028 0.4430 0.4212 0.4562 0.42600.4465 0.4071 0.4259 0.3583 0.4342 0.4028 0.4465 0.4071 0.4373 0.3893 8A0.4373 0.3893 8B 0.4465 0.4071 8C 0.4582 0.4099 8D 0.4483 0.3919 0.44650.4071 0.4562 0.4260 0.4687 0.4289 0.4582 0.4099 0.4582 0.4099 0.46870.4289 0.4813 0.4319 0.4700 0.4126 0.4483 0.3919 0.4582 0.4099 0.47000.4126 0.4593 0.3944

According to some embodiments, a desired emitter group region may bedefined by a standard, such as the ANSI C78.377A LED binning standard,Table A1 of which is reproduced below:

TABLE 2 ANSI C78.377A Table A1 2700 K 3000 K 3500 K 4000 K x y x y x y xy Center point 0.4578 0.4101 0.4338 0.4030 0.4073 0.3917 0.3818 0.3787Tolerance 0.4813 0.4319 0.4562 0.4260 0.4299 0.4165 0.4006 0.4044Quadrangle 0.4562 0.4260 0.4299 0.4165 0.3996 0.4015 0.3736 0.38740.4373 0.3893 0.4147 0.3814 0.3889 0.3690 0.3670 0.3578 0.4593 0.39440.4373 0.3893 0.4147 0.3814 0.3898 0.3716 4500 K 5000 K 5700 K 6500 K xy x y x y x y Center point 0.3611 0.3658 0.3447 0.3553 0.3287 0.34170.3123 0.3282 Tolerance 0.3736 0.3874 0.3551 0.3760 0.3376 0.3616 0.32050.3481 Quadrangle 0.3548 0.3736 0.3376 0.3616 0.3207 0.3462 0.30280.3304 0.3512 0.3465 0.3366 0.3369 0.3222 0.3243 0.3068 0.3113 0.36700.3578 0.3515 0.3487 0.3366 0.3369 0.3221 0.3261

Conventionally, to ensure that combined light emitted by a package fallswithin a standard chromaticity region, or bin, only light emitters thatfall within the standard bin are chosen for inclusion within thepackage, and other light emitters that do not fall within the standardbin are discarded or ignored. However, some embodiments enable theselection and use of light emitters having chromaticity points that falloutside a standard bin to be used in a package that emits combined lighthaving a chromaticity point within the standard bin, and in some cases,within a chromaticity region that is even smaller than the standard bin.As used herein, a “bin” refers to a defined region of a chromaticityspace. Typically, LEDs are sorted into defined bins for manufacturingpurposes based on the chromaticity of light emitted by the LEDs, in aprocess referred to as “binning.” In the ANSI C78.377A standard, binsare defined as quadrangles that inscribe a 7-step MacAdam ellipse. Thatis, the quadrangles have widths about the same as a major axis of a7-step MacAdam ellipse centered within the quadrangle, which is thestandard tolerance defined for compact fluorescent lamps by theDepartment of Energy Energy Star program. However, because the bins aredefined as quadrangles, some chromaticity points that fall within thebin may nevertheless fall outside the 7 step MacAdam ellipse used todefine the bin. Thus, in packaging methods in which light emitters aresimply selected from a desired bin, some packaged LEDs can emit lightthat falls within the defined bin that has a visibly different colorfrom other packaged LEDs that also emit light that falls within the bin.It will be appreciated that bins can be defined as shapes other thanquadrangles. For example, bins could be defined as ellipses such asMacAdam ellipses, triangles, circles or any other geometric shape.Furthermore, bins can be defined in any color space, including a 1931CIE (x,y) color space, a 1976 CIE (u′,v′) color space, or any othercolor space.

In some embodiments, the standard bins can be further subdivided intoeven smaller bins that can be used to define chromaticities. Forexample, FIG. 6B illustrates standard chromaticity bins definedaccording to the ANSI C78.377A LED binning standard that have beenfurther subdivided into smaller bins. Smaller bins offer improved colorconsistency among LED lighting fixtures. In some embodiments, 4 sub-binsmay be defined within each ANSI quadrangle. In further embodiments, oneor more of the warm/neutral ANSI quadrangles may be sub-divided into 16discrete sub-bins, each of which may be 94 percent smaller than thequadrangles defined in the ANSI C78.377A LED binning standard. It willbe appreciated, therefore, that the at least three sub-bins from whichthe LEDs are selected can be non-contiguous within the region.

Referring to FIG. 7, a standard bin 150 defined in the ANSI C78.377A LEDbinning standard is shown. According to some embodiments, a chromaticityregion 146 is defined. The chromaticity region 146 may defined ascontiguous with the defined bin 150 in some embodiments. In otherembodiments, as illustrated in FIG. 7, the chromaticity region 146 maybe larger than and encompass the defined bin 150, such that the definedbin 150 is a subset of the chromaticity region 146. Although thechromaticity region 146 illustrated in FIG. 7 is a quadrangle, it willbe appreciated that other geometric shapes may be used to define thechromaticity region. The chromaticity region 146 is further subdividedinto a plurality of subregions 146A-146D, each of which may at leastpartially overlap the standard bin 150. However, subregions may bedefined that do not overlap the standard bin 150. Light emitters120A-120D having chromaticities within one or more of the definedsubregions 146A-146D may then be selected for inclusion in an LEDpackage.

The light emitters 120A-120D may, for example, have respectivechromaticity points at the points indicated in FIG. 7. In the example ofFIG. 7, the chromaticity point of light emitter 120A is within thesubregion 146A, but is on the edge of the defined bin 150. Thechromaticity point of the light emitter 120B is within the subregion146B and within the desired bin 150. Similarly, the chromaticity pointof the light emitter 120C is within the subregion 146C and within thedesired bin 150. The chromaticity point of light emitter 120D is withinthe subregion 146D, but is outside the desired bin 150. However, thecombined light emitted by all four light emitters 120A-120D may bewithin the desired bin 150, and may be within an even smaller targetchromaticity region 148 that is within the defined bin 150.

In particular, for a chromaticity region 146 that is defined contiguouswith an ANSI-specified bin, a target chromaticity region 148 can beobtained according to some embodiments that approximates a 4-stepMacAdam ellipse, thereby providing significantly better color puritycompared to a package that is simply specified as falling within theANSI-specified bin. A 4-step MacAdam ellipse provides approximately thelevel color purity that is available from standard T8, T10 and T12fluorescent lamps.

In some embodiments, a target chromaticity region 148 can be obtainedthat is approximately the size of a 2-step MacAdam ellipse throughappropriate selection of light emitters. A 2-step MacAdam ellipseprovides approximately the level color purity that is available fromstandard halogen and incandescent lamps. In further embodiments, atarget chromaticity region 148 can be obtained that is even smaller thana 2-step MacAdam ellipse.

In some embodiments, a chromaticity region is defined that encompasses adefined bin. The chromaticity region is divided into subregions, each ofwhich at least partially overlaps the defined bin. Light emitters areselected from the subregions for inclusion within an LED package. Foreach of the defined subregions, there may be a complementary subregionthat is arranged opposite a center point of the defined bin from thesubregion. For example, referring to FIG. 7, subregions 146A and 146Dare complementary subregions, since they are disposed opposite oneanother relative to a center point 145 of the defined bin 150, andsubregions 146C and 146B are complementary subregions. In selectinglight emitters for inclusion in an LED package 100, whenever a lightemitter is selected from a subregion, a light emitter may also beselected from a complementary subregion for inclusion within aparticular LED package 100.

By selecting light emitters from multiple defined subregions within achromaticity region, the final combined light output by a packaged LED100 may be more consistent (i.e. more tightly grouped) than if the lightemitters had simply been selected from an arbitrary point within thechromaticity region. In some embodiments, it has been found that animprovement in grouping of combined light chromaticities of up to 79% ormore can be achieved.

In general, the target chromaticity region 148 can be determined as theunion of all possible chromaticity points of light that is generated bya combination of one light emitter from each of the subregions146A-146D. Thus, the outer perimeter of the target chromaticity region148 can be determined by combining light from four different lightemitters at the extreme points of the respective subregions 146-146D.For example, referring to FIG. 8A, assuming equal luminous flux, lightemitters 120A-120D having chromaticity points at the extreme positionsshown therein will generate combined light having a chromaticity point160A. That is, for a selection of one light emitter from each of thefour defined subregions 146A to 146D, FIG. 8A represents a worst-case ormost extreme scenario of chromaticity points for the four lightemitters. However, as illustrated in FIG. 8A, the chromaticity point160A of the combined light may still fall well within the defined bin150

Similarly, referring to FIG. 8B, assuming equal luminous flux, lightemitters 120A-120D having chromaticity points at the extreme positionsshown therein will generate combined light having a chromaticity point160B, which is still within the defined bin 150. Taking all possiblecombinations of four light emitters from the four different subregions146A to 146D will define the target chromaticity region 148 as a regionof all possible chromaticity points of combined light that can beobtained from a combination of light emitters including one lightemitter from each of the subregions 146A-146D.

In some particular embodiments, the size of the chromaticity region 146,which can be used to define the bins 146A-146D from which light emittersare selected, can be determined so that any combination of lightemitters from the four different subregions 146A-146D will not generatecombined light having a chromaticity point that falls outside thedefined bin 150. That is, the size of the chromaticity region 146 can beselected so that the target chromaticity region 148 touches an edge ofthe defined bin 150, as illustrated in FIG. 8C.

Thus, according to some embodiments, an LED package 100 can generatecombined light having a chromaticity that is inside a desired bin eventhough the package 100 includes one or more light emitters havingchromaticities outside the desired bin. This approach can providesignificant flexibility to an LED package manufacturer, because itenables the use of larger bins of light emitters than was previouslypossible. This can reduce waste and inefficiency in the packagingprocess, because there may be fewer unusable parts compared to amanufacturing process in which only light emitters from a defined binare selected for inclusion in a package designed to emit light having acolor point within the region occupied by the defined bin.

A system for assembling LED packages according to some embodiments isillustrated in FIG. 9. As shown therein, a pick and place device 500 isconfigured to accept a plurality of die sheets 510A to 510D. Each of thedie sheets 510A to 510D includes light emitters 120A to 120D that emitlight that falls within one of the subregions 146A to 146D of thechromaticity region 146. For example, light emitters 120A on the diesheet 510A may emit light that falls within the first subregion 146A ofthe chromaticity region 146, light emitters 120B on the die sheet 510Bmay emit light that falls within the second subregion 146B of thechromaticity region 146, etc.

In some embodiments, the pick and place device 500 may accept a singledie sheet 510A that includes light emitters from each of the subregions146A-146D along with an electronic die map 520 containing informationabout the chromaticities of the various die on the die sheet 510A.

In some embodiments, one or more of the die sheets 510A-510D may containlight emitters that include LED die that have been coated with aphosphor containing material.

The pick and place device 500 also receives a plurality of packagebodies 110, for example on a tape reel. The pick and place device 500may select one light emitter 120A-120D from each of the die sheets510A-510D and mount it on a single package body 110. The package body110 including the four light emitters 120A-120D is then output by thepick and place device 500 to a subsequent processing device, forexample, to coat the light emitters 120A-120D with an encapsulant, toaffix a lens onto the package body 110, or to perform some other action.

Accordingly, a manufacturing process according to some embodiments canfacilitate efficient assembly of an LED package 100 that includes lightemitters selected to generate a combined light that falls within atarget chromaticity region.

In addition to chromaticity, luminous flux may be considered in groupingthe light emitters 120. For example, reference is now made to FIG. 10,which is a table illustrating luminous flux bin values according to someembodiments of the present invention. The light emitters 120 may begrouped according to their luminous flux using multiple luminous fluxranges. For example, three luminous flux bins identified as V1, V2, andV3 may correspond to ranges 100 lm to 110 lm, 110 lm to 120 lm, and 120lm to 130 lm, respectively. In this manner, emitter groups may bedefined as falling within a specific chromaticity subregion at aspecific luminous flux range. For example, an emitter group may includeall light emitters 120 having chromaticity corresponding to chromaticitysubregion 146C and luminous flux V2. Thus, the light emitters 120 may begrouped responsive to a combined chromaticity of a portion of multiplebins that may be defined corresponding to multiple chromaticity regionsand multiple luminous flux ranges.

Reference is now made to FIG. 11, which is a chromaticity diagramillustrating multiple chromaticity regions and a target chromaticityregion according to some embodiments of the present invention. A portionof 1931 CIE chromaticity space 460 includes an x axis 464 and a y axis462. Light emitters 120 may be sorted into multiple chromaticitysubregions 468 according to the chromaticity of light emitted therefrom.In some embodiments, the chromaticity regions 468 may fall within aregion that is generally considered to constitute white light. A targetchromaticity region 470 may include a portion of the chromaticity region460 that is specified corresponding to a design specification and/or aparticular application. In some embodiments, the target chromaticityregion 470 may be expressed in terms of chromaticity coordinates. Insome embodiments, a tolerance color region 472 may be larger than thetarget chromaticity region 470 due to variations between individualemitters within each of the subregions 468.

In some embodiments, each of the emitter group regions 468 may include acenter point that may be determined as a function of chromaticityvalues. Some embodiments provide that, within each bin, the emitters maybe further grouped corresponding to luminous flux. In this regard, eachof the bins may be expressed, for example, in terms of x, y, and Y, suchthat chromaticity of each of the bins may be expressed as center pointx, y coordinates and the luminous flux may be expressed as Y.

A combined chromaticity corresponding to emitters from two bins may bedetermined using the chromaticity and luminous flux center point valuescorresponding to the two bins. For example, the combined chromaticitycomponent values for mixing two bins, bin 1 and bin 2, may be calculatedas:

$\begin{matrix}{{{x = \frac{{x\; 1*m\; 1} + {x\; 2*m\; 2}}{{m\; 1} + {m\; 2}}};{and}}{{y = \frac{{y\; 1*m\; 1} + {y\; 2*m\; 2}}{{m\; 1} + {m\; 2}}},}} & (1)\end{matrix}$such that x1 and y1 are chromaticity center point values of bin 1, andx2 and y2 and chromaticity center point values of bin 2. Intermediatevalues m1 and m2 may be used to incorporate the center point luminousflux values Y1 and Y2 of bins 1 and 2, respectively, into the combinedchromaticity component values and may be determined as:

$\begin{matrix}{{{{m\; 1} = \frac{Y\; 1}{y\; 1}};{and}}{{m\; 2} = {\frac{Y\; 2}{y\; 2}.}}} & (2)\end{matrix}$

In some embodiments, a combined luminous flux corresponding to thecombination of bins 1 and 2 may be determined as:Y=Y1+Y2.  (3)

In some embodiments, combinations that produce a luminous flux below aspecified range may be discarded. In some embodiments, the luminous fluxvalues of the bins are such that a combined luminous flux is necessarilywithin a specified range. For example, if the minimum bin luminous fluxis V1 and the specified range includes V1 luminosities, then all of thecombinations necessarily are within the specified range. Although thedisclosure herein specifically addresses two bin combinations, theinvention is not thus limited. For example, combinations including threeor more bins may also be used according to the methods, devices andapparatus disclosed herein.

After filtering out combinations based on luminous flux, if necessary,the combined chromaticity of each two-bin combination may be compared toa target chromaticity region 470 to determine which of the combinationsto discard. For example, if a combined chromaticity is located inemitter group region A3 then that combination may be discarded. In thismanner, the combinations that provide sufficient luminous flux andchromaticity may be considered when selecting the light emitters 120from corresponding ones of those bins.

In some embodiments, the multiple bins may be prioritized based on, forexample, proximity to the target chromaticity region 470. For example,bins that are farther from the desired color region may be assigned ahigher priority than bins that are nearer to the desired color region.In this manner, subregion A9 may be assigned a higher priority thansubregion C3. In some embodiments, combination center points may then beprioritized corresponding to the bin priorities.

Some embodiments provide that the combination center points may beprioritized based on locations of the combination center points relativeto a target chromaticity point in the target chromaticity region 470. Insome embodiments, the target chromaticity may be dependent on thegeometry of desired color region, such as, for example, a center and/orother focus point of the target chromaticity region 470. In someembodiments, the light emitters 120 are selected from a batch orinventory of light emitters that are grouped into the bins and thetarget chromaticity point may correlate to chromaticity and/or luminousflux data of the emitter inventory.

Selection and combination of light emitting devices may be performedaccording to the methods described in U.S. patent application Ser. No.12/057,748, filed Mar. 28, 2008, the disclosure of which is incorporatedherein as if fully set forth in its entirety.

Referring to FIG. 12, a lighting panel 600 includes a plurality of LEDpackages 100 as described herein that are mounted on a first side of thepanel 600 and that emit light combined 610 having a chromaticity withina target chromaticity region for use in general lighting applications.

FIG. 13 is a flowchart illustrating operations according to someembodiments. As illustrated therein (with further reference to FIG. 7),methods of forming a light emitting device package assembly according tosome embodiments include providing a light emitting device package body(Block 702), defining a chromaticity region in a two dimensionalchromaticity space and subdividing the defined chromaticity region intoat least three chromaticity subregions (Block 704), and providing aplurality of light emitting devices that emit light having achromaticity that falls within the defined chromaticity region (Block706). At least three of the plurality of light emitting devices areselected for mounting on the light emitting device package body, whereineach of the three light emitting devices emits light from a differentone of the chromaticity subregions (Block 708). Finally, the selectedLEDs are mounted on the package body (Block 710)

The methods may further include defining a second chromaticity region ina two dimensional chromaticity space and subdividing the secondchromaticity region into at least three second chromaticity subregions,providing a second plurality of light emitting devices that emit lighthaving a chromaticity that falls within at least one of the secondchromaticity subregions, and, selecting at least three of the secondplurality of light emitting devices, wherein each of the three lightemitting devices of the second plurality of light emitting devices emitslight from a different one of the second chromaticity subregions. Theselected light emitting devices of the second plurality of lightemitting devices are mounted on the light emitting device package body.Accordingly, the operations illustrated in Blocks 702 to 710 of FIG. 13can be repeated and/or performed concurrently for a second or subsequentchromaticity regions.

As discussed above, the defined subregions may include a plurality ofpairs of complementary subregions with respective subregions in a pairof complementary subregions arranged opposite a center point of thechromaticity region from one another. The methods may further includeselecting at least four of the plurality of light emitting devices fromat least four chromaticity subregions in pairs from respective pairs ofcomplementary subregions.

As used herein, the term “complementary subregions” refers to twosubregions arranged on opposite sides of a target chromaticity point, sothat a line from at least one point in a first one of the complementarysubregions to at least one point in a second one of the complementarysubregions passes through the target chromaticity point. Three or moresubregions are complementary if a polygon defined by the center pointsof the subregions encloses the target chromaticity point.

Similarly, two light emitting devices are complementary if a linethrough the chromaticity points of the two light emitters passes througha target chromaticity region, such as a 2-step, 4-step or 7-step MacAdamellipse, around the target chromaticity point. Three or more lightemitting devices are complementary if a polygon defined by thechromaticity points of the light emitting devices encloses the targetchromaticity point.

Furthermore, the methods may include selecting a first light emittingdevice having a first luminous flux from a first subregion that has acenter point that is located a first distance from a center point of thechromaticity region, and selecting a second light emitting device havinga second luminous flux from a second subregion that is complementary tothe first subregion and that has a center point that is located a seconddistance from a center point of the chromaticity region. The firstdistance may be smaller than the second distance and the first luminousflux may be larger than the second luminous flux, so that combined lightemitted by the pair of light emitting device from complementarysubregions may fall within the target chromaticity region, asillustrated in FIG. 11.

Referring again to FIG. 7, by selecting sets of light emitting devicesthat are complementary to one another in terms of chromaticity andluminous flux for inclusion in a device or system, a target chromaticityregion 148 can be obtained that is even smaller than a 4-step MacAdamellipse. For example, a target chromaticity region 148 can be obtainedthat is approximately the size of a 2-step MacAdam ellipse or smaller.For example, FIGS. 14A, 14B and 14C illustrate examples in whichcomplementary light emitters are selected from a plurality of subregionswithin a defined region.

Referring to FIG. 14A, which illustrates a portion of a two-dimensionalchromaticity space, a quadrangular chromaticity region 800 is definedthat approximately corresponds to the 3000K bin defined in Table A1 ofANSI standard C78.377A. In FIG. 14A, the chromaticity region 800 hasbeen subdivided into 16 approximately equal-sized quadrangularsubregions 801.

The target chromaticity point is assumed to be the central point of thechromaticity region 800, which is at a (CCx, CCy) of (0.4342, 0.4028).

A first pair of complementary light emitters 802A, 802B having similarluminous flux ratings, and a second pair of complementary light emitters804A, 804B having similar luminous flux ratings, may be selected fromfour different ones of the subregions 801 and combined in a package.

Using equation (3) above and assuming the light emitters 802A, 802B,804A and 804B have luminous flux ratings and chromaticity points shownin Table 3 below, the combined light emitted by the packaged device mayhave a chromaticity point 806 at a (CCx, CCy) chromaticity point of(0.4337, 0.4021), which is near the target chromaticity point at thecenter of the chromaticity region 800.

TABLE 3 Chromaticity Points - Example 1 Point CCx CCy Flux 802A 0.4270750.403975 93.9 lm 802B 0.441125 0.401525 93.9 lm 804A 0.419375 0.386693.9 lm 804B 0.4505 0.420025 93.9 lm

A set of complementary light emitters may include more than two lightemitters. For example, in the embodiments illustrated in FIG. 14B, afirst complementary set of two light emitters 802A, 802B is provided asin the previous example, and a second set of three complementary lightemitters 808A, 808B, and 808C is also provided.

Using equation (3) above and assuming the light emitters 802A, 802B,808A, 808B and 808C have luminous flux ratings and chromaticity pointsshown in Table 4 below, the combined light emitted by the packageddevice may have a chromaticity point 810 that is near the center of thequadrangle 800 at a (CCx, CCy) chromaticity point of (0.4348, 0.4033).

TABLE 4 Chromaticity Points - Example 2 Point CCx CCy Flux 802A 0.4270750.403975 93.9 lm 802B 0.441125 0.401525 93.9 lm 808A 0.419375 0.3866 107 lm 808B 0.4505 0.420025 93.9 lm 808C 0.439475 0.408425 93.9 lm

As shown in FIG. 14B, the set of complementary light emitters 808A, 808Band 808C includes two lower-flux light emitters 808B, 808C on one sideof the target chromaticity point and one higher flux light emitter 808Aon an opposite side of the target chromaticity point. The presence oftwo lower flux light emitters 808B, 808C on one side of the targetchromaticity point and one higher flux light emitter 808A on an oppositeside of the target chromaticity point, but located relatively far fromthe target chromaticity point, helps to balance the color point of thecombined devices near the target color point at the center of thechromaticity region 800.

Similarly, in the embodiments illustrated in FIG. 14C, a firstcomplementary set of two light emitters 802A, 802B is provided as in theprevious example, and a second set of four complementary light emitters812A, 812B, 812C and 812D is also provided, with light emitters 812A and812D having the same chromaticity point.

Using equation (3) above and assuming the light emitters 802A, 802B,812A, 812B, 812C and 812D have luminous flux ratings and chromaticitypoints shown in Table 5 below, the combined light emitted by thepackaged device may have a chromaticity point 816 that is near thecenter of the quadrangle 800 at a (CCx, CCy) chromaticity point of(0.4328, 0.4012).

TABLE 5 Chromaticity Points - Example 3 Point CCx CCy Flux 802A 0.4270750.403975 93.9 lm 802B 0.441125 0.401525 93.9 lm 812A 0.419375 0.386693.9 lm 812B 0.4505 0.420025  100 lm 812C 0.439475 0.408425  107 lm 812D0.419375 0.3866 93.9 lm

As shown in FIG. 14C, the set of complementary light emitters 812A,812B, 812C and 812D includes two lower-flux light emitters 812A, D onone side of the target chromaticity point and two higher flux lightemitter 812B, 812C on an opposite side of the target chromaticity point.The presence of two lower flux light emitters 812A, 812D on one side ofthe target chromaticity point and two higher flux light emitter 812B,812C on an opposite side of the target chromaticity point, with onehigher flux light emitter 812C located relatively close to the targetchromaticity point, helps to balance the color point of the combineddevices near the target color point at the center of the chromaticityregion 800.

In the embodiments illustrated in FIG. 14D, a first complementary set oftwo light emitters 802A, 802B is provided as in the previous example,and a second set of three complementary light emitters 818A, 818B, and818C is also provided.

Using equation (3) above and assuming the light emitters 802A, 802B,818A, 818B and 818C have luminous flux ratings and chromaticity pointsshown in Table 6 below, the combined light emitted by the packageddevice may have a chromaticity point 820 that is near the center of thequadrangle 800 at a (CCx, CCy) chromaticity point of (0.4348, 0.4033).

TABLE 6 Chromaticity Points - Example 4 Point CCx CCy Flux 802A 0.4270750.403975 93.9 lm 802B 0.441125 0.401525 93.9 lm 818A 0.419375 0.3866 107 lm 818B 0.44575 0.410625 93.9 lm 818C 0.444 0.4177 93.9 lm

As shown in FIG. 14D, the set of complementary light emitters 818A, 818Band 818C includes two lower-flux light emitters 818B, 818C on one sideof the target chromaticity point and one higher flux light emitter 818Aon an opposite side of the target chromaticity point. The presence oftwo lower flux light emitters 818B, 818C on one side of the targetchromaticity point and one higher flux light emitter 818A on an oppositeside of the target chromaticity point, but located relatively far fromthe target chromaticity point, helps to balance the color point of thecombined devices near the target color point at the center of thechromaticity region 800.

In the embodiments illustrated in FIG. 14E, a single set of threecomplementary light emitters 828A, 828B, and 828C is provided.

Using equation (3) above and assuming the light emitters 828A, 828B and828C have luminous flux ratings and chromaticity points shown in Table 7below, the combined light emitted by the packaged device may have achromaticity point 830 that is near the center of the quadrangle 800 ata (CCx, CCy) chromaticity point of (0.4352, 0.4037).

TABLE 7 Chromaticity Points - Example 5 Point CCx CCy Flux 828A 0.4193750.3866  107 lm 828B 0.44575 0.410625 93.9 lm 828C 0.444 0.4177 93.9 lm

In the embodiments illustrated in FIG. 14F, a single set of threecomplementary light emitters 838A, 838B, and 838C is provided. Thecomplementary light emitters 838A, 838B, and 838C are selected fromsubregions 81 that are complementary as a group, but that are notcomplementary in pairs.

Using equation (3) above and assuming the light emitters 838A, 838B and838C have luminous flux ratings and chromaticity points shown in Table 8below, the combined light emitted by the packaged device may have achromaticity point 840 that is near the center of the quadrangle 800 ata (CCx, CCy) chromaticity point of (0.4330, 0.4015).

TABLE 8 Chromaticity Points - Example 6 Point CCx CCy Flux 838A 0.4193750.3866 93.9 lm  838B 0.4411 0.4015 107 lm 838C 0.4375 0.4154 107 lm

In particular embodiments, each of the sets of complementary lightemitters may, as a set, emit combined light when energized having achromaticity that is within a 2-step MacAdam ellipse of a targetchromaticity point. Accordingly, a combined light emitted by the overalldevice 100 including all of the light emitters may have a chromaticitythat is within a 2-step MacAdam ellipse of the target chromaticitypoint.

Methods according to some embodiments can be applied not only tounpackaged light emitting devices that are assembled into a package, butalso to packaged light emitting devices, including multi-chip lightemitting devices, that are assembled in luminaire or lighting fixture.For example, referring again to FIG. 12, a luminaire, such as thelighting panel 600, includes a plurality of packaged LEDs 100 that aremounted on a first side of the panel 600 and that emit light combined610 having a chromaticity within a target chromaticity region for use ingeneral lighting applications.

In some embodiments, each of the packaged LEDs 100 emits light having aparticular chromaticity point, which may be a combined light emitted bya plurality of light emitting devices selected for inclusion in thepackage in accordance with the methods described herein. The packagedLEDs 100 may themselves be binned into chromaticity regions/subregionsand selected for inclusion in the luminaire 600 in accordance with themethods described herein so as to provide a luminaire 600 that generatesa desired color of light.

In the drawings and specification, there have been disclosed typicalembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being set forth inthe following claims.

1. A method of forming a light emitting device assembly, comprising:providing a light emitting device assembly body; defining a chromaticityregion in a two dimensional chromaticity space wherein the chromaticityregion is defined within a 10-step MacAdam ellipse of a targetchromaticity point, and subdividing the defined chromaticity region intoat least three chromaticity subregions; providing a plurality of lightemitting devices that emit light having a chromaticity that falls withinthe defined chromaticity region; selecting at least three of theplurality of light emitting devices, wherein each of the three lightemitting devices has a chromaticity point in a different one of thechromaticity subregions and wherein the at least three light emittingdevices are selected from chromaticity subregions that are complementaryrelative to the target chromaticity point to at least one otherchromaticity subregion from which a light emitting device is selected;and mounting the selected light emitting devices on the light emittingdevice assembly body, wherein selecting the at least three lightemitting devices comprises selecting at least two sets of light emittingdevices, wherein each set of light emitting devices comprises at leasttwo light emitting devices selected from chromaticity subregions thatare complementary relative to the target chromaticity point, wherein thechromaticity region encompasses a defined bin in the two dimensionalchromaticity space, and the defined bin comprises a quadrangle on a twodimensional chromaticity space, wherein each of the at least threechromaticity subregions at least partially overlaps the defined bin. 2.The method of claim 1, wherein the target chromaticity point is on theblack body locus and has a correlated color temperature between 2600Kand 6600K.
 3. The method of claim 1, wherein combined light from the atleast three light emitting devices falls within a target chromaticityregion that is a subset of the defined bin.
 4. The method of claim 3,wherein the defined chromaticity region is larger than and encompassesthe defined bin, and wherein the target chromaticity region touches anedge of the defined bin.
 5. The method of claim 3, wherein the targetchromaticity region has an area on a two dimensional chromaticity spacethat is about the size of a 2-step MacAdam ellipse in the twodimensional chromaticity space.
 6. The method of claim 3, wherein thetarget chromaticity region has an area on a two dimensional chromaticityspace that is smaller than a 2-step MacAdam ellipse in the twodimensional chromaticity space.
 7. The method of claim 1, wherein thelight emitting devices comprise phosphor-coated blue light emittingdevice chips.
 8. A method of forming a light emitting device assembly,comprising: providing a light emitting device assembly body; defining achromaticity region in a two dimensional chromaticity space wherein thechromaticity region is defined within a 10-step MacAdam ellipse of atarget chromaticity point, and subdividing the defined chromaticityregion into at least three chromaticity subregions; providing aplurality of light emitting devices that emit light having achromaticity that falls within the defined chromaticity region;selecting at least three of the plurality of light emitting devices,wherein each of the three light emitting devices has a chromaticitypoint in a different one of the chromaticity subregions and wherein theat least three light emitting devices are selected from chromaticitysubregions that are complementary relative to the target chromaticitypoint to at least one other chromaticity subregion from which a lightemitting device is selected; and mounting the selected light emittingdevices on the light emitting device assembly body, wherein thechromaticity region comprises a first chromaticity region, and theplurality of light emitting devices comprises a first plurality of lightemitting devices, the method further comprising: defining a secondchromaticity region in a two dimensional chromaticity space wherein thesecond chromaticity region is defined within a 10-step MacAdam ellipseof a second target chromaticity point and wherein the secondchromaticity region does not overlap with the first chromaticity region,and subdividing the second chromaticity region into at least threesecond chromaticity subregions; providing a second plurality of lightemitting devices that emit light having a chromaticity that falls withinat least one of the second chromaticity subregions; selecting at leastthree of the second plurality of light emitting devices, wherein each ofthe three light emitting devices of the second plurality of lightemitting devices emits light from a different one of the secondchromaticity subregions; and mounting the selected light emittingdevices of the second plurality of light emitting devices on the lightemitting device package body.
 9. The method of claim 8, wherein thesecond chromaticity region comprises light having a dominant wavelengthgreater than about 600 nm.
 10. The method of claim 8, furthercomprising: defining a third chromaticity region in a two dimensionalchromaticity space, and subdividing the third chromaticity region intoat least three third chromaticity subregions wherein the thirdchromaticity region does not overlap with the first and/or secondchromaticity regions; providing a third plurality of light emittingdevices that emit light having a chromaticity that falls within at leastone of the third chromaticity subregions; selecting at least three ofthe third plurality of light emitting devices, wherein each of the threelight emitting devices of the third plurality of light emitting devicesemits light from a different one of the third chromaticity subregions;and mounting the selected light emitting devices of the third pluralityof light emitting devices on the light emitting device package body. 11.The method of claim 10, wherein the first chromaticity region compriseslight having a chromaticity point that is within a 10-step MacAdamellipse of a point on the black body locus having a correlated colortemperature between 2600K and 6600K, the second chromaticity regioncomprises light having a dominant wavelength greater than about 600 nm,and the third chromaticity region comprises light having x, y colorcoordinates within an area on a 1931 CIE Chromaticity Diagram defined bypoints having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45),(0.42, 0.42), (0.36, 0.38).
 12. The method of claim 1, wherein thedefined subregions comprise a plurality of pairs of complementarysubregions, wherein respective subregions in a pair of complementarysubregions are arranged opposite a center point of the chromaticityregion from one another, wherein selecting the at least three of theplurality of light emitting devices comprises selecting at least four ofthe plurality of light emitting devices from at least four chromaticitysubregions in pairs from respective pairs of complementary subregions.13. A method of forming a light emitting device assembly, comprising:providing a light emitting device assembly body; defining a chromaticityregion in a two dimensional chromaticity space wherein the chromaticityregion is defined within a 10-step MacAdam ellipse of a targetchromaticity point, and subdividing the defined chromaticity region intoat least three chromaticity subregions; providing a plurality of lightemitting devices that emit light having a chromaticity that falls withinthe defined chromaticity region; selecting at least three of theplurality of light emitting devices, wherein each of the three lightemitting devices has a chromaticity point in a different one of thechromaticity subregions and wherein the at least three light emittingdevices are selected from chromaticity subregions that are complementaryrelative to the target chromaticity point to at least one otherchromaticity subregion from which a light emitting device is selected;mounting the selected light emitting devices on the light emittingdevice assembly body, wherein the defined subregions comprise aplurality of pairs of complementary subregions, wherein respectivesubregions in a pair of complementary subregions are arranged opposite acenter point of the chromaticity region from one another, whereinselecting the at least three of the plurality of light emitting devicescomprises selecting at least four of the plurality of light emittingdevices from at least four chromaticity subregions in pairs fromrespective pairs of complementary subregions, and wherein selecting apair of light emitting device from one pair of complementary subregionscomprises selecting a first light emitting device having a firstluminous flux from a first subregion that has a center point that islocated a first distance from a center point of the chromaticity region,and selecting a second light emitting device having a second luminousflux from a second subregion that is complementary to the firstsubregion and that has a center point that is located a second distancefrom a center point of the chromaticity region, wherein the firstdistance is smaller than the second distance and wherein the firstluminous flux is larger than the second luminous flux.
 14. The method ofclaim 1, wherein the at least three light emitting devices are selectedfrom at least three chromaticity subregions that are complementaryrelative to the target chromaticity point.
 15. A light emitting deviceassembly, comprising: a light emitting device assembly body; and atleast three light emitting devices on the assembly body, wherein each ofthe at least three light emitting devices emits light having achromaticity that falls within a defined chromaticity region in a twodimensional chromaticity space wherein the chromaticity region isdefined within a 10-step MacAdam ellipse of a target chromaticity pointthat is on the black body locus and that has a correlated colortemperature between 2600K and 6600K, the defined chromaticity regionbeing subdivided into at least three chromaticity subregions, whereinthe at least three light emitting devices emit light when energized thatfalls within chromaticity subregions that are complementary relative tothe target chromaticity point to at least one other chromaticitysubregion in which a light emitting device in the light emitting deviceassembly emits light; wherein the at least three light emitting deviceson the assembly body comprises at least two sets of light emittingdevices, wherein each set of light emitting devices comprises at leasttwo light emitting devices selected from chromaticity subregions thatare complementary relative to the target chromaticity point, wherein thechromaticity region encompasses a defined bin in the two dimensionalchromaticity space, and the defined bin comprises a quadrangle on a twodimensional chromaticity space, wherein each of the at least threechromaticity subregions at least partially overlaps the defined bin.